Respiratory viral infections, particularly by human rhinoviruses (HRV), play important roles in inception, development, exacerbation and chronicity of asthma. This program is focused on defining interactions between factors regulating HRV replication and host immune response to viral infection that affect the severity of associated respiratory illness. Each of the projects will use viral diagnostics, and Projects II and 111 require specialized preparations of purified viruses and molecular reagents related to viral biology. The Virology Core is established to provide viral diagnostics and HRV molecular reagents to each of the three proposed projects. Project I will be supported with a repertoire of sensitive and accurate molecular detection assays to identify all common respiratory viruses and the individual species/type/strain of HRV. The viral loads will be quantified by qPCR in a subset of HRV-positive nasal samples from human subjects of Project I for subsequent virus isolation, complete genome sequencing, cDNA cloning and use in Projects ll-lll. In addition, this core will support the in vitro experiments of Projects l-lll by supplying (1) high-titer and uniform HRV virus stocks, including purified viruses (native, radiolabeled and inactivated) of selected HRV serotypes and strains, infected cell lysates of 100 classical HRV-A and HRV-B serotypes and newly identified HRV-C strains, (2) various anti-HRV antibodies, (3) cDNA clones (infectious, chimeric, reporter, replicons) of selected HRV-A, HRV-B and HRV-C types/strains, (4) performing infectivity assays (plaque and TCID50), and (5) culture of airway epithelial cells.